1. Field of the Invention
The present invention relates to a solid-state imaging device.
2. Description of the Related Art
An amplification type solid-state imaging device being one type of solid-state imaging device transfers a charge generated at a photoelectric conversion portion of each pixel to an input node of an amplifying transistor via a transfer portion.
When the charge is transferred, noise can be reduced if the charge of the photoelectric conversion portion is completely transferred. Japanese Patent Application Laid-Open No. 2005-192191 discusses a method useful for increasing the maximum amount of charge that can be transferred from the photoelectric conversion portion.
According to the solid-state imaging device discussed in Japanese Patent Application Laid-Open No. 2005-192191, before starting the transfer of charge from a photodiode to a floating diffusion (FD), the voltage of the FD is set at a higher value than the voltage of the FD when it is reset. However, the control of the voltage of the FD when a signal is output from an amplifying transistor after the charge has been transferred is not discussed.
According to an amplification type solid-state imaging device, it is desirable to operate the amplifier circuit within an operation range where the linearity of the output signal is good. According to the solid-state imaging device discussed in Japanese Patent Application Laid-Open No. 2005-192191, if the voltage of the FD is high, in some cases, the amplifying transistor operates in a linear region, or the amplifying transistor operates in a boundary region of a saturation region and the linear region. In order to maintain the linearity of the output signal, it is desirable to operate the amplifying transistor in the saturation region. Thus, the solid-state imaging device discussed in Japanese Patent Application Laid-Open No. 2005-192191 has room for improvement from the viewpoint of linearity of the signal output from the amplifying transistor.